For those that are worried about grade in any of Carnaby's...

For those that are worried about grade in any of Carnaby's copper deposits I suggest a look at the work Caravel is doing on its Definitive feasibility study on the Caravel copper project. I am also a bit old school and like to see high copper grade above 1% however many large mines around the world operate on far lower grades. There is always a trade off between tonnage and grade, lower grade you need more tonnes to get economies of scale to make things profitable and lower tonnes you need higher grade to deal with the higher mining costs and lesser economies of scale.

Caravel is 150km NE of Perth. They are working on 25+ years producing 65,000tpa copper and 900tpa molybdenum. The astonishing part is that they believe the economics work on a 1.18 billion tonne orebody grading only 0.24% copper (over 2Mt Cu in ground). They are looking at 30Mtpa processing with a molybdenum circuit as well as the copper. Capex: AUD$1.7 billion. AISC US$2.07/lb. Payback 4.9 years.

I am not an investor in Caravel and 0.24% Cu does not work for me because I would feel very vulnerable to copper price fluctuations but it shows how far the grade curve of the worlds copper mines has shifted and the low grade starting point the industry is beginning to consider.

If Carnaby use a 0.24% Cu cut-off at Nil Desperandum the open pit tonnage would grow considerably over using a 0.5% or higher cut-off as there are large halo lower grade zones of copper mineralisation although these have not really been targeted by CNB. For underground I assume 0.7-1.0 % Cu cut-off grade is more realistic given the ore geometry at Nil Desperandum. I am not sure there is much halo lower grade mineralisation at Mount Hope, Lady Fanny or Burke and Wills.

I am not in any way suggesting Carnaby can get the tonnage up to the same order of magnitude as Caravel, I just don't see this. Mt Isa copper was around 230-300Mt at 3% Cu from memory.

DYOR. Not investment advice.